This invention relates to a method of testing dielectric ceramic capacitors, and more particularly, to a destructive test procedure for multi-layer capacitors.
Ceramic dielectric capacitors are manufactured and widely used. These capacitors are employed in numerous applications, and high reliability for such capacitors is very important. As a consequence, there has been a significant degree of attention directed to testing of capacitors in order to weed out those which may fail under normal operating conditions. Such tests include numerous procedures which apply excessive stress beyond the operating conditions normally encountered by the capacitor.
Multi-layer ceramic dielectric capacitors may use piezoelectric material as the dielectric. One common capacitor manufactured of a piece of electric dielectric is identified as an X7R type. These capacitors are widely used, and in at least one application, that identified as a frequency synthesizer, approximately 1600 capacitors are used.
A standard test employed for such capacitors is known as the dielectric withstanding voltage (DWV) test. In this test, a voltage approximately 2.5 times the rated voltage of the capacitor is applied to the capacitor. The current which flows through the capacitor is generally of low value, and the common test specs for the DWV test merely require application of this test voltage. It has been discovered that this test, among others, does not adequately weed out potentially faulty multi-layer ceramic dielectric capacitors. In fact, with current test procedures, the above described synthesizer capacitor components experience a failure rate of 1% during burn-in.
An object of this invention is to provide such a test procedure which provides that capacitors which pass the test have enhanced reliability.
Another object of this procedure is to provide such a procedure which uses relatively conventional techniques, so as to minimize the training required to perform such tests.
Still another object of this invention is to provide such a test which is quick, efficient, yet only passes capacitors having the highest reliability.
Other objects, advantages and features of this invention will become more apparent from the following description.